Method of operating retorts to produce coke, gas, and oil



Jan. 7, 1936.

A. W. WARNER METHOD OF OPERATING RETORTS TO PRODUCE COKE, GAS AND OILOriginal Filed Oct. 27, 1951 l-leaflrg Zone Cool/n5 Zon Gaseousproalcxis of comusic'on d .Phsfa'c cone 1565 yases s 3 n /0 I] 457dlZd/OI 6km flieam arwl aaes fiffeaml sji iun Go K 2 emu lNVENTOR BY mg&

ATTORNEYS Patented Jan. 7,

PATENT OFFICE METHOD OF OPERATING RETORTS TO PRODUCE "COKE, GAS, AND 01LArthur Woodward Warner, Media, Pat, assignor to Isbell Porter Company,Newark, N. J a corporation of New York ded and this application February2, 1933, Serial No. 654,891

3 Claims. (01. 292-15) This invention relates broadly to operatingmethods for coking retorts for the purpose of producing high grade coke,low temperature oils and fuel gas from coking coals. I

One of the important objects of this invention involves methods forproducing and'controlling the plastic gas resistant barrier which formsin coking retorts-at the point of transition of the coal into coke.

A further object of this invention is the provision of methods for usein treatment of coking fuels in which an accurate control of thereaction is obtained for the continuous production of uniform coke, gasand oil.

Another object of this invention involves a method of maintaining aplastic barrier which forms when coal is coked so that the gases formedwithin the barrier may readily escape to the outside thereof.

A still further object of this invention is to form and control the sizeand position of the plastic barrier and maintain it vented in order tosecure uniform products and uniform operation conditions.

Another object of this invention involves the control of the plasticbarrier or film so as to keep the vapors formed on each side thereofseparated until they are beyond the heating zone.

An additional object of this invention involves the formation of theplastic barrier in a column -of coking fuel, the venting thereof, andthe removal of the gases formed or introduced within the barrier fromnear the top of the column so that the fuel is preheated before itreaches the coking zone. a

- A still further object of this invention involves the control of theplastic barrier by control of the throughput of both coal and'heatinggases for the purpose of producing a high grade coke of relatively highvolatile content while main-.

taining the production of gaseous products at a minimum. I

These and many other objects as will appear from the followingdisclosure are secured by means of this invention.

This invention resides substantially in the steps and series of steps aswill be apparent from th following description:

This application is a division of my co pending application, Serial No.571,332, filed, October 27, 1931.

Referring to the drawing the single featureis a vertical cross sectionalview through the apparatus of this invention illustrated diagram;matically. a

The apparatus and method of this invention.

relate to and involve the heat treatment of solid carbonaceous fuels,such asjcoal, lignite, oil, shale and the like, and particularly cokingcoals for the purpose of producing therefrom high grade coke of uniformsize, low temperature oils and gaseous fuels. The invention may beapplied to continuous'internally heated retorts, regardless of thesource of heat, whether generated within the charge or externally. Incoking retorts of this type it has been found that at the-surface oftransition of the coal into coke a plastic barrier or film forms whichis more or less gas impervious. This film is composed of melted coalwhich is produced at a temperature of around 750 degrees F. The film orbarrier is in a plastic state and normally has a thickness ofapproximately one-quarter of an inch. This barrier of melted coal existsbetween the uncoked coal and the formed coke.

It has been found that the formation of this film is the cause. of thedifficulties normally encountered in the production of coke at eitherhigh or low temperatures in continuous internally heated retorts.Because the film is gas impervious, the gaseous products formed withinit are not easily removed and as a result a back pressure is built upwithin the retort. Furthermore, the formation of this film has beenfound to be the cause of, thelack of uniformity in the operation of suchretorts and the products produced thereby.-

' The prime object of this invention is to employ this very barrier orfilm for the purpose of producing uniform operation and uniformproducts.

In-both externally and internally heated continuous retorts the plasticbarrier occurs in the form of an inverted cone with the apex pointingdownwardly. By means of this invention the position of the cone isreversed and its apex is vented to permit the escape of the gaseousproducts formed within it. Venting of the plastic cone is effected byfeeding a central core of coke into the retort in such a manner as tomaintain the top of the cone open so that the gaseous products formedwithin it may pass freely through thegas pervious cokgcore.

In ordina'rflntemally heated continuous vertical retorts, especiallywhen using fine sized coking coal, this plastic hollow, unvented conetends to shift about in the retort varying both its size and pfiitionunder different operating conditions so that itis impossible to produceuniform products and uniform operating conditions. 23y means of thisinvention the position ofthe plastic cone is relatively, fixed and itssize is controlled to aid in producing uniform products and operatingconditions.

The retort which may be constructed in ac-- suitable discharge apparatussuch as is shown in s the drawing comprising a caslng- 2 within whichare mounted rotatable discharge gates 3. The. top of the retort isprovided with a cover 4 which is shown as provided with a dependingskirt 4 and upwardly extending feed hoppers 4 provided with covers I".It is likewise apparent that the form of'feeding mechanism employed maybe of any of the well known types. The general characteristic of thefeeding mechanism is merely that it shall be able to feed the coalcontinuously into the retortwithout substantially opening the retort tothe atmosphere. There are many known types of continuous feed hoppersfor such retorts. Extending centrally through the cover 4 is a tube 6 ofany suitable cross section and provided with a cove 1. This tube isver-, tically slidable through e cover. The top of the retort isprovided with gas take-off connections 5 of which only one is shown.

Extending around the retort near the base of the heating zone, is atuyere provided with\; a series of discharge connections 9opening'directly into the retort. Just below the tuyre 8 is a secondtuvere "likewise provided with space discharge connections ll openinginto the retort. At It is a connection into the retort provided with anozzle by means of which steam, or any suitable neutral gas, may bedischarged into the retort.

As indicated in the drawing the retort may be divided into three zones.The lower zone is termed the "cooling zone" in which the coke and otherresidue is gradually cooled. In the next zone, called the heating zone,the fuel is heated either by the introduction of sensible heat throughthe tuyeres or by direct combustion to a temperature to liberate thegaseous productsthereof. The last zone is called the "pre-heating zone"and represents the volume where the fresh incoming fuel is heated by thegases ascending from the heating zone. In the pre-heating zone, forweakly coking coals, the higher boiling point volatiles may be made tocondense on the relatively cold incoming fresh fuel. The heaviestcondensation products flow back toward the heating zone where they arecracked down into simpler forms and revolatilized, thereby augmentingthe deficient coke forming constituents of the coal.

The method of this invention and the apparatus disclosed operatescontinuously. In other words, fuel is continuously fed into the top andtravels continuously downwardly through the retort and out at thebottom. As already stated, there are many known forms of feeding anddischarging mechanism for eifecting such a continuous operation.

In the operation of this retort the heating zone may be maintainedeither by combustion or by the passage of highly heated gasestherethroughl In the form of apparatus shown in the drawing hot producergas or other suitable heated gases may be introduced into the retort bymeans of tuyre 8. Air and/or steam may be introduced in o the retortthrough the tuyere Ill where the combustion type of internally heatedretort is employed to aid in complete combustion and to effect thecontrol of temperature at the combustion zone.

' When a temperature of approximately 750 de- 5 grees F. is attained inthe retort and by any method of heating, the plastic film forms whichhas been indicated diagrammatically at It in the form of a truncatedcone. This film separates the uncoked coal from the formed coke at thecenter. The coke which is fed through pipe 6 forms a center core whichmaintains the top of the plastic cone l3 vented so thatthe gases formedwithin the cone may readily escape asindicated by the arrows. In thisinvention this cone is employed to keep the gases formed each side ofthe cone separated until they. reach a point where their temperature hasfallen to a value where no harm results from their intermixturex. Inother words, the low temperature volatiles formed outside of the plasticcone do not mix with the high temperature volatiles formed within theplastic zone until they get above the upper end of the cone at whichtime they may be \mixed without degradation of the low temperature oils.The center core of coke maintains the top of the plastic -cone ventedpermitting easy escape of the gases formed within the cone. The heatedgases rising through the upper portion of -the retort through thepre'heating zone act to pre-heat'the fresh incoming coal in thepreparation for coking before they are withdrawn through the connection5. The incoming coal is normally pre-heated sufllciently to avoid allcondensation of water and oil within the heating zone.

Previous attempts to improve the notoriously, inefilcient methods ofproducing coke have been directed more with a view to adapting theparticular coals to a given retort rather than to 40 modifying theretort or the operation thereof to produce the proper conditions forefilcient production of high grade coke. It will be apparent that thepresent method is directed to an improved method of operating cokingretorts to 4,5 adapt the method to the raw material to produce thedesired operation and results.

In prior practice, one dimculty of operating coking retorts has residedin the fact that uniform operating conditions could not be maintained.As is well known in the operation of coking retorts, of eithertheinternally or the externally heated type, a plastic film formed whicheffectively sealed off the cross sectional area of the retort. This filmis produced by the melting of the coal when it attains a temperature ofthe order of 750 degrees F. under which condition it is forming intocoke. This film is highly resistant to gas flow and prevents theattainment of the proper through-put of heated gases necessary 6 to theproduction of high grade coke. This film continually breaks through andheals up, varying the resistance to flow of the heating gases anddestroying the smooth operation. This film has taken the form of aninverted or dependent 66 plastic cone around which the heated gasesascended without proper diffusion through the fuel column.

This invention is carried on in a continuous internally heated retort insuch away that what 70 was formerly a dependent cone now becomes anupright cone which is vented at the top and maintained vented so thatthe heating gases will flow against a substantially constant resistance,

namely, that formed by the fuel only. 76

' cone and the gaseous products are taken of! near or at the top of thecolumn so that they must flow upwardly through the top of the columnwhich is composed of fresh, incoming coal. The heated gases leaving theheating zone flow upwardly through-the coal and pre-heat it. This is atremendously important feature of this invention, because it enables theproduction of high grade coke at a maximum rate.

By venting the top of the cone and by introducing the heating gases atthe base of the heating zone, at the proper temperature and volume,

it is possible to pro-heat the coal to approximately 700 regress F.(near or at its melting temperature) before it reaches the heating zone.This requires that the heating gases enter the preheating zone at about900 degrees F. and leave the retort at about 200 degrees F. with thefresh coal entering at about 60 degrees F., and with a proper volume ofheating gases these results can be obtained. It is only by venting thetop of the cone that it is now possible to increase the volume of thethrough-put to a value where these tem-' perature conditions can beuniformly attained and maintained. It requires a large volume of gas perton of coal to produce these results which amount can only be putthrough the retort when the top of the cone is vented. This would beroughly 50,000 cubic feet of gas per ton, having an entering temperatureof the order of 1120 degrees F.

With this invention about 80% of the heat of carbonization of the coalis supplied thereto in the pro-heating zone and before melting starts,leaving approximately 20% to be added to the fuel in the heating zone.The pre-heating zone acts similar to a reflux condenserfor all oilsexcept the'pitch fraction which alone undergoes destructive distillationas it descends into the heating zone. The result is, that the coal isuniformly saturated which is a necessary condition for the production ofuniform coke structure. Furthermore, this method of operation preventsswelling of the coal which is so disastrous to proper operation.

With this method, when dealing with weakly coking coals where strongercoke structure is required, the temperature of the heating gases wouldbe raised and the volume per ton reduced, thereby reducing the amount ofpro-heat. The result would be the return of the heavier pitch residuesto the coking zone to augment the coke forming constituents in the coal.Thus the coke quality would be improved at the expense of the oil yield.This is illustrative of the fact that the retort controls are varied tosuit the coal as distinguished from the present practice where the coalsare blended or otherwise treated to suit the retort.

It is important to note that the key to uniform strong coke formation isthe absence of re-vaporization at the coking zone which is made possibleby pro-heat.

At this point it is interesting to note that a portion of the gaseousproducts after having the oils condensed therefrom and washed, maybedelivered back into the retort through the tu- The height of theeone\lii is determined by the coal throughput, the volume of the heatedgases and the heat potential thereof; the lower the coal through-put,the shorter the cone; the greater the volume of the through-put heating5 gases, the shorter the cone, and the ,lower the po-- 'tential of theheating gases, the shorter the cone.

through-put of the heating gases can be main- 1-5 tained either byincreased heat potential and less volume. or by larger volume at lessheat potential. The plastic zone terminates at the point where thetemperature of the coking fuels falls below 750 degrees The tube 6 ismade vertically adjustable so that the upper end of the cone l t hasbeen maintained vented regardless of its vertical extent.

1 While coke is preferably fed through tube t because it does notcontaminate the finished product, it is apparent that lumps of anynon-melting substance could be used for this purpose such as rock andthe like. The center core of coke is fed downwardly continuously withthe fresh incoming fuel to maintain a gas pervious center core atancitbeyond the point where the coal begins to me As the coke and otherresidue descends below the heating zone, it is cooled by dischargingsteam, or any neutral gas into it through pipe l2 and its attachednozzle. By cooling the coke in a zone below the heating zone, by theintroduction of a gas, the gas is super-heated as it rises through theheating zones and mixes with the hot products produced in the heatingzone to thereby t0 form a vehicle for suitably distributing heat in boththe heating and pro-heating zones. The coked product is finallydischarged after cooling from the retort through the dischargemechanism.

Another advantage of this method and apparat5 tus which causes theformation of the plastic cone as'shown is that the cone of coke withinthe plastic film is surrounded by a compacted cup of coal so that thecoke is continuously sub- Jected to pressure. As aresult the coke cannotexpand and deteriorate as in the case of previous apparatus where thecone is inverted so that the coke is in the form of an outside cup witha center core of coal. I In all continuous retorts the retorts are ta- 5pered to facilitate easy discharge. This invention allows any taperdesired without disturbing the coke during formation. The loose coal iscontinuously taking up the extra space made by the taper and does notallow the coke to swell; that is, does not make the coke too porous.

From the foregoing description it will be apparent that this inventionresides in certain forms of apparatus and principles of operation whichmay be embodied by those skilled in the art in other ways withoutdeparture from the invention.

I do not, therefore, desire to be strictly limited to the disclosure asgiven for purpose of illustration but rather to the scope of theappended claims.

What I seek to secure by United States Letters Patent is:

1. A method of coking coal in a continuous internally heated retortcomprising feeding coal into the retort to form a column thereof, ig-

niting the column at one end to form a combustion zone, forcing oxygenbearing gases into the combustion zone to maintain it and coke the coal,introducing coke into the central portion of the column above thecombustion zone to form a core for the column, removing the gasesgenerated in the column from the top, thereof,

said gases passing through coal column, and removing the residue fromthe bottom of the column, whereby an upstanding plastic film of conicalshape of melted coal is formed and maintained vented at the apex of thecoke core.

2. A method of coking coal in a continuous internally heated retortcomprising feeding coking coal into the retort to form a column thereof,discharging coke into the retort to form a central core for the columnof coal, introducing gases heated above the fusion temperature into thecolumn to form a heating zone in the column, removing the gasesgenerated in or introduced into the column from the top thereof andshielding the coke core to make it gas impervious to a point below thetop of the column, whereby an upstanding plastic conical film of meltedcoal isformedvented attheapexby theookecorc and gases generated orintroduced within the film flow upwardly throughthe vented 'top of thefilm and through the unshielded part of core into and upwardly throughthe column to the I point of gas removal from the column.

3. A method of destructively distilling coking coal in a continuousinternally heated retort to control the compactness of the coke formedand uniformity of the oil yield comprising feeding lo coking coal intothe retort to form a column thereof, maintaining a fusion zone at thebase of the column with heated gases, feeding coke in a column into thecoal column centrally thereof to form a gas pervious core therefor,removing the 15 gases from the retort at the top of the coal column,shielding the coke core to vary the length of the gas pervious portionand controlling the amount of heated gas and the amount of shielding ofthe coke core, whereby a maximum amount to of pre-heating of the coalcolumn occurs before the coal reaches the fusion zone.

ARTHUR WOODWARD WARNER.

